TOKYO (AP) — About 1,400 people filed a joint lawsuit Thursday against three companies that manufactured reactors at Japan's Fukushima Dai-ichi nuclear plant, saying they should be financially liable for damage caused by their 2011 meltdowns.

Lawyers for the plaintiffs said the lawsuit, filed at Tokyo District Court, is a landmark challenge of current regulations that give manufacturers immunity from liability in nuclear accidents. Under Japan's nuclear damage compensation policy, only the operator of the plant, Tokyo Electric Power Co., has been held responsible for the accident, which was triggered by a powerful earthquake and tsunami.

The 1,415 plaintiffs, including 38 Fukushima residents and 357 people from outside Japan, said the manufacturers — Toshiba, GE and Hitachi — failed to make needed safety improvements to the four decade-old reactors at the Fukushima plant. They are seeking compensation of 100 yen ($1) each, saying their main goal is to raise awareness of the problem.

Akihiro Shima, a lawyer for the group, said the manufacturers have not been held responsible "and their names are not even mentioned." The lawsuit intends to bring attention to the system that protects the nuclear industry around the world, he said.

The four reactors all began operation in the 1970s. Units 1, 3 and 4 were built by GE, Toshiba and Hitachi, respectively, while Unit 2 was a joint GE-Toshiba project. GE and Hitachi later established GE Hitachi Nuclear Energy.

Several accident investigation reports, including one published by a parliament-appointed panel, have generally agreed that the tsunami was the primary cause of the disaster, but also criticized TEPCO's underestimation of potential tsunami damage and collusion between regulators and the nuclear industry.

Citing those reports, Christopher White, spokesman for GE Hitachi Nuclear Energy, said the accident was caused by the tsunami and the resulting loss of power and reactor cooling, not reactor design.

The design of the four affected Fukushima reactors "has proven to be safe for more than 40 years around the globe," White said. He said the nuclear industry is working to further improve "an already safe set of technologies," including the installation of better backup power supplies and cooling systems.

Toshiba and Hitachi declined to comment on the lawsuit, saying they have not received the legal documents.

The Fukushima plant has largely stabilized since the accident, but TEPCO continues to struggle with leaks of massive amounts of radioactive water from the wrecked reactors into the Pacific Ocean. The decommissioning of the four damaged reactors, including three with melted cores, is unprecedented in terms of its extent and complexity, and could take decades.